Sunday, September 20, 2009

2.375" Motor Casing Completed

I finished the casing for the motor. I realized that I made a mistake in the CAD drawing that I posted earlier today. There should be six retaining screws for both the nozzle and the bulkhead versus twelve. I also made a slight change to the length of the casing, opting to make it 3/4"shorter which allowed me to true the ends on the lathe. I hadn't planned on being able to do that but by turning the tool post backwards I was able to extend it's capacity by just enough. Since just a very light cut was needed this worked fine. The design is pretty generous in the propellant segment spacing, so I'll make up the deficit by reducing the spacing slightly.
The bottom photo shows the new extended casing next to the older motor design. The new casing still has it's rust preventive zinc coating. The coating doesn't add any structural strength and has a fairly low melting point so I'll remove it with a quick dip in some muriatic acid.

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